In domestic animals, handling and transport are known to be potent stressors (Stephens, 1980: and Kenny et al., 1987). Such stresses are often termed "antemortem stresses". These stresses have been documented to bring about changes in many physiological parameters including thermoregulation (Frens, 1975; and Houdas et al., 1975). It is also well documented that such factors as handling, mixing, and transport in the preslaughter environment (the "antemortem environment") are causative agents of poor meat quality (Jones et al., 1989; Jones et al., 1988; Warriss, 1986). Primarily affected are such quality attributes as colour, moisture holding capacity, pH, toughness and texture. If the stress is severe enough, the animal's energy supply is taxed, which in turn may lead to poor or degraded meat quality, such as dark, firm and dry (DFD) or tough meat in beef cattle, or pale, soft and exudative (PSE) meat in swine
The assessment of meat quality has always, by necessity, been done on post mortem analysis. To the inventors' knowledge, prior to their own invention, as set forth in U.S. application Ser. No. 084,993, filed Jul. 2, 1993, now U.S. Pat. No. 5,458,418. (PCT Application No. PCT/CA94/00383, published Jan. 12, 1995) there has never been a technology with a demonstrated capability to detect animals likely to produce poor meat quality. Arguably, the development or discovery of such a technology capable of predicting meat quality in live animals in the antemortem environment has significant value to the meat production industry, since preventative and restorative therapy can be initiated in those identified animals.
Infrared thermography (IRT) has been used in human medicine for some time for the diagnosis and study of such conditions as tumors and cardiovascular integrity (Clark et al., 1972) as well as hyperthermia (Hayward et al., 1975). In domestic animals, IRT has also been found useful for diagnosing such conditions as vascular lesions in pigs (Lamarque et al., 1975) and leg injuries in horses (Clark et al., 1972).
The patent literature discloses the use of IRT for several purposes. U.S. Pat. No. 3,877,818 to Button et al., discloses the use of IRT for determining fat content in meat (post mortem). U.S. Pat. No. 3,948,249 to Ambrosini teaches 8 the use of an infrared detector for identifying a cow in heat. U.S. Pat. No. 5,017,019 to Pompei discloses the use of radiation detectors to measure temperature differentials in animals.
The inventors have been involved in previous studies using IRT with live animals. Initial studies by the co-inventors Jones, Schaefer and Gariepy suggested that IRT might be useful in identifying basic stress levels in cattle (Schaefer et al., 1987a, 1988) and in swine (Schaefer et al., 1987b; and Gariepy et al., 1987). The studies recognized that cattle having cooler surface temperatures as measured by IRT appear to have lower meat quality, while in pigs, poor meat quality was associated with very high surface temperatures. However, these studies fell short of teaching a method for reliably detecting the likelihood of poor meat quality in live animals.
There is a continuing need for a method of detecting, with acceptable accuracy, live animals susceptible to producing poor meat quality.